Author: Chuck
Date: 6/22/2009 8:54 am EDT
I use a piece of plastic saran wrap and push it down against the surface of the grout and then put the lid on with the excess plastic wrap sticking out under the lid. This eliminates any contact with air at the surface of the grout and you don't need to push the lid on tight. This works for any material that will dry out such as wall patch.